The present invention relates to a pneumatic tire provided with a sealant layer on an inner surface of the tire in a region corresponding to a tread portion of the tire, and more specifically relates to a pneumatic tire capable of suppressing a flow of a sealant in the sealant layer due to a centrifugal force generated during the running of the tire.
There are pneumatic tires each provided with a sealant layer on an inner surface of the tire in a region corresponding to a tread portion of the tire. A sealant contained in the sealant layer is generally composed of a compound which is not crosslinked. Thus, the sealant has appropriate viscosity and fluidity for the sealing of a hole, which would be formed by a foreign substance, such as a nail, getting stuck in the tread portion.
However, in the pneumatic tire including the sealant layer, the sealant sometimes flows toward the tread center due to a centrifugal force during the running of the tire, so that the amount of sealant is reduced near the shoulders of the tire. Such a formation of a portion where the amount of sealant is locally reduced in the sealant layer not only reduces the sealing performance, but also deteriorates the weight balance of the entire tire, possibly causing a problem in that vibrations are likely to occur.
In view of the above-described problems, an approach has been proposed in which a sealant layer is divided into a plurality of portions with partition walls in a width direction of the tire, so that a flow of the sealant in the sealant layer in the width direction of the tire is suppressed (see, for example, Japanese patent application Kokai publication Nos. 2003-285376, 2003-334868, and Hei. 6-226870).
However, dividing a sealant layer into a plurality of portions with partition walls in a width direction of the tire is significantly difficult to implement in actual manufacture of tires, and accordingly has not yet been put into practice in the current situation.